JPH09188569A - Defatting of ceramic compact and defatting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defatting method capable of suppressing occurrence of defect of a product and producing good-quality products in high productivity and a defatting apparatus. SOLUTION: A non-oxidizing atmospheric gas A having oxygen partial pressure lower than oxidation-reduction equilibrium oxygen partial pressure of metal powder in a ceramic compact 21 is previously heated by a preheater 12 and air is fed from one direction and discharged without recycling and a flow rate of the nonoxidizig atmospheric gas per min at 0 deg.C under 1 atom pressure is set to a flow rate equal to or lager than whole space volume of a supporting container 11 for supporting the ceramic compact 21 and the ceramic compact 21 is defatted in the above conditions, when the ceramic compact 21 composed of ceramic powder, metal powder of the internal electrode and an organic binder is heated and the organic binder is removed from the ceramic compact 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degreasing method and a degreasing apparatus for decomposing and volatilizing an organic binder (binder, plasticizer, lubricant, etc.) of a ceramic molded body by heating, and more specifically, it will be described. The present invention relates to a degreasing method for an integrated-sintering type electronic component of electrodes and ceramics, such as a multilayer ceramic capacitor, and a degreasing apparatus used for the method.

[0002]

2. Description of the Related Art In recent years, as electronic devices such as radios, microcassette recorders, electronic tuners, and video cameras have become ultra-small, thin, and lightweight, there is a strong demand for miniaturization and large capacity of electronic components used as circuit elements. It's starting to happen.

A monolithic ceramic capacitor, for example, is known as a ceramic electronic component of an integrally sintered type in which an electrode and a ceramic satisfy these requirements. The manufacturing method of a monolithic ceramic capacitor is as follows. First, a ceramic dielectric green sheet having a thickness of several tens of μm is formed on an organic film by a doctor blade method using a slurry consisting of a dielectric powder, a binder, a plasticizer and an organic solvent. To do. Next, an internal electrode is printed on this ceramic dielectric green sheet, a plurality of sheets excluding the organic film are stacked, and then a laminated molded body is manufactured by pressure bonding. Further, this laminated molded body is cut into chips, degreased and sintered, and then external electrodes are attached to complete the production.

By the way, in the conventional technique, atmospheric air is usually used for the degreasing method of the ceramic molded body. When degreasing is performed using the atmosphere, the organic binder rapidly generates heat due to oxidative decomposition and causes thermal runaway, and the metal powder in the ceramic compact is oxidatively expanded. As a result, defects are induced in the internal structure of the product.

In order to suppress defects in the internal structure of this product, in the conventional method, the temperature distribution of the ceramic molded body in the apparatus was made uniform and the temperature was raised over time.
For example, in the case of multilayer ceramic capacitors, 400 ° C
It took 40 hours to reach the heat treatment temperature (10 ° C./h heating rate). Moreover, it is generally necessary to adjust the temperature distribution of the ceramic molded body during this temperature raising process within about ± 10 ° C.

Further, in this degreasing process, usually, a supporting container for supporting the ceramic molded body is arranged at an interval for the purpose of uniform temperature, and an internal circulation type in which gas in the apparatus is stirred by a motor fan or the like. A degreasing device is provided. The details of the internal circulation type degreasing device will be described later with reference to FIG.

[0007]

However, such a conventional degreasing method and degreasing apparatus have a problem that the productivity per unit scale and unit time is low, and the product manufacturing cost is increased. ing. In addition, the conventional method of degreasing by using an internal circulation type degreasing device that stirs the gas in the device with a motor fan etc. is that the degreased exhaust gas decomposed and volatilized from the ceramic molded body by heating contacts the ceramic molded body surface again. Therefore, there is a problem in that they cause compound defects and the like on the structure of the product.

An object of the present invention is to provide a degreasing method and a degreasing apparatus capable of suppressing the occurrence of product defects and producing high quality products with high productivity.

[0009]

In order to achieve the above object, the method for degreasing a ceramic molded body according to claim 1 of the present invention comprises a ceramic powder, a metal powder as an internal electrode, and an organic binder. When the ceramic molded body is heated to remove the organic binder from the ceramic molded body, the oxidation-reduction equilibrium of the metal powder of the internal electrode in the ceramic molded body is adjusted to a predetermined value with a non-oxidizing atmospheric gas having an oxygen partial pressure lower than the oxygen partial pressure. The gas is heated to a temperature, the gas is blown from one direction to a support container that supports the ceramic molded body, and the gas is discharged without being recirculated.
The converted flow rate per minute of 1 atm is set to a flow rate equal to or higher than the total space volume of the container.

The degreasing method for a ceramic molded body according to a second aspect of the present invention is the degreasing method according to the first aspect, wherein the dew point of the non-oxidizing atmosphere gas is 40 ° C. or higher.

According to a fifth aspect of the present invention, in a degreasing device for a ceramic molded body, the ceramic molded body composed of the ceramic powder, the metal powder as an internal electrode, and an organic binder is heated to remove the ceramic molded body from the ceramic molded body. A degreasing device used when removing an organic binder, the degreasing device main body accommodating a support container for supporting a ceramic molded body, and the degreasing device main body at a converted flow rate per minute of 0 ° C. and 1 atm. , A mechanism for supplying an atmospheric gas in a volume not less than the entire space of the support container supporting the ceramic molded body, a mechanism for heating the atmospheric gas to a predetermined temperature in advance, and a non-oxidizing atmospheric gas blown from one direction. And a mechanism for discharging without recirculation.

The degreasing device for a ceramic molded body according to claim 6 of the present invention is characterized in that the degreasing device according to claim 5 is provided with a mechanism for humidifying atmospheric gas. In the degreasing device for a ceramic molded body according to claim 7 of the present invention, the degreasing device main body is formed in a cylindrical shape, and a fan-shaped support container for supporting the ceramic molded body is laminated in a cylindrical shape inside the degreasing device main body. It is characterized by As a method for degreasing a ceramic molded body and a method for molding a ceramic molded body targeted for the degreasing apparatus of the present invention, conventional molding methods such as a sheet laminating method, an injection molding method, and an extrusion molding method can be used.

As the ceramic powder, oxides such as barium titanate, titanium oxide and barium oxide, nitrides such as silicon nitride and aluminum nitride, carbides such as silicon carbide and titanium carbide, and mixtures of these compounds are conventionally used. be able to.

As the organic binder, butyral resin,
Conventionally used resins such as acrylic resins and styrene resins, and mixtures of these resins with a plasticizer can be used.

In the method for degreasing a ceramic molded body of the present invention, firstly, as the atmospheric gas, a non-oxidizing atmospheric gas having an oxygen partial pressure lower than the oxygen reduction equilibrium oxygen partial pressure of the metal powder in the ceramic molded body is used. It is characterized by being done.

Generally, as the oxygen partial pressure is lowered during the degreasing process, the decomposition of the organic binder in the ceramic molded body is more dominated by the endothermic reaction than the oxidative decomposition. In principle, thermal runaway due to heat generation can be suppressed. In principle, the oxidative expansion of the metal powder was eliminated by using a non-oxidizing atmosphere gas having an oxygen partial pressure lower than the redox equilibrium oxygen partial pressure of the metal powder.

Further, in the degreasing treatment under a low oxygen partial pressure, degreasing efficiency is further improved by using an atmosphere gas having a dew point of 40 ° C. or higher. As a result, it is possible to increase the temperature rising rate as compared with the conventional method while suppressing the internal structural defects of the product.
Moreover, since the influence of the temperature distribution does not need to be considered so much as compared with the conventional method, it is possible to arrange a support container that supports a larger number of ceramic compacts in the apparatus. Therefore, the productivity per unit scale and unit time can be significantly improved.

Further, among the causes of internal structural defects such as cracks and swelling that occur when degreasing is performed by the conventional method, thermal runaway due to heat generation due to oxidative decomposition of the above-mentioned organic binder and metal in the ceramic molded body The present inventors have conducted detailed research on causes other than the oxidative expansion of the powder, and have come to the following conclusions.

When the ceramic molded body is heated in a non-oxidizing atmosphere gas, the organic binder in the ceramic molded body volatilizes in the form of highly reactive low-molecular organic matter mainly due to thermal decomposition. Furthermore, this low-molecular organic substance is particularly highly reactive with the surface of the ceramic powder, and if a normal circulation type degreasing device is used, the low-molecular organic substance carried by the circulating air flow is highly likely to be re-applied to the surface of the ceramic powder. Will be attached. When the low-molecular organic matter redeposits on the surface and combines, the ceramic compact becomes hard and brittle, and as a result,
As a result, the probability that defects such as cracks and swelling will occur due to the subsequent sintering process increases. Therefore, it can be said that it is necessary and important in order to obtain a good quality product that the probability that the volatilized low-molecular organic matter, in other words, the degreased exhaust gas, redeposits on the surface of the ceramic compact is as low as possible.

To solve this problem, in the present invention, as a concrete means for reducing the probability of the above-mentioned degreased exhaust gas re-adhering to the surface of the ceramic molded body, first, a non-oxidizing atmosphere gas is used for the ceramic molding. The air was blown into the support container supporting the body from one direction and was discharged so that the atmospheric gas was not recirculated inside the degreasing apparatus main body.
Further, the atmospheric gas was adjusted to a predetermined temperature in advance and forcedly passed through the main body of the degreasing apparatus to perform heating, and at the same time, natural convection in the apparatus was suppressed as much as possible.

[0021]

1 (a) is a schematic front view of a degreasing apparatus according to the first embodiment, and FIG. 1 (b) is an X- line in FIG. 1 (a).
The Y line sectional view is shown.

The degreasing apparatus used in the degreasing method according to the present invention has a ceramic molded body supporting container 11 arranged therein,
It is composed of a degreasing device main body B having a preheater 13 on the outer periphery, a gas flow rate controller 14 for adjusting the flow rate of the gas flowing out from the nitrogen gas cylinder 15 and the hydrogen gas cylinder 16, and a gas preheater 12 for preheating the gas. ing. In the present embodiment, a mass flow meter is specifically used as the gas flow rate controller 14.

Nitrogen gas cylinder 15 for supplying atmospheric gas
The flow rate of the non-oxidizing atmosphere gas A flowing out from the hydrogen gas cylinder 16 is adjusted by the gas flow rate controller 14 and flows from the right side to the left side in FIG. Next, the non-oxidizing atmosphere gas A whose flow rate has been adjusted is heated and adjusted to a predetermined temperature by the gas preheating heater 12. The non-oxidizing atmosphere gas A adjusted to a predetermined flow rate and temperature is then supplied from one end of a support container 11 [hereinafter referred to as the support container 11] that supports the ceramic molded body disposed inside the degreasing apparatus body B. It flows in and is discharged from the other end without recirculation.

The preliminary heater 13 arranged in the degreasing apparatus main body B is used as an auxiliary when the capacity of the gas preheating heater 12 is insufficient due to a predetermined temperature and heating speed condition, and in principle, it is not used. It doesn't matter.

Support container 11 in the first embodiment
As shown in FIG. 1 (c), the stacking is performed in 9 steps in the height direction, 5 steps in the length direction and 3 steps in the width direction, and a total of 135 support containers 11 are provided inside the degreasing apparatus main body B. It is stacked without any gaps.

The individual support containers 11 are formed as shown in FIG. The vertical cross section of the support container 11 has a channel shape, and when the ceramic molded body 21 to be degreased is loaded and then stacked as shown in FIG. It is devised to ensure a flow path for flow.

The support container 11 used in this embodiment is
It is made of alumina and has a width of 10 cm, a length of 15 cm and a height of 3 cm. However, the size, quantity, shape, and material of the support container 11 may be any as long as they satisfy the condition that the flow path through which the atmospheric gas passes can be secured even after the ceramic molded bodies 21 are stacked after being stacked. It goes without saying that is not limited.

[Experimental Example 1] Next, Experimental Example 1 using the degreasing apparatus will be described. First, the ceramic molded body 21 to be degreased will be described. At the time of manufacturing the molded body 21, by a doctor blade method, using a dielectric slurry composed of a dielectric powder containing barium titanate as a main component and having a particle size of about 1.5 μm, and an organic binder containing butyral resin as a main component. A sheet having a dry thickness of 30 μm was prepared. Further, a commercially available Ni electrode paste was used to print an internal electrode having a dry thickness of 3 μm thereon by a screen printing method to obtain a green sheet. After stacking 20 of these green sheets, press them together and further 2mm
It was cut into a shape of × 4 mm to obtain a ceramic molded body.
The organic binder component contained in this ceramic compact was 10 wt%. In this experimental example, a ceramic molded body 21 of a multilayer ceramic capacitor chip (hereinafter referred to as Ni multilayer chip) having Ni as an internal electrode is used.
It is.

In Experimental Example 1, 100 g of the above-mentioned Ni laminated chip was loaded on one support container 11, and 9 steps in the height direction, 5 steps in the length direction and the width direction as shown in FIG. 1 (c). Degreasing was carried out by arranging three stages, totaling 135 pieces, in the degreasing apparatus body B without any gap.

The total space volume of the container 11 supporting the ceramic molded body 21 in the present invention means the support container 1
1 means the sum of the actual volume, the volume of the ceramic molded body 21 itself, and the volume of the space in which the atmospheric gas flows, and the total space volume of the support container 11 in this experimental example is 60750 cm. ³ (= 10c
m × 15 cm × 3 cm × 135 = 60.75 liters).

To this sample, a non-oxidizing atmosphere gas having an oxygen partial pressure lower than the redox equilibrium oxygen partial pressure of Ni metal, which is the main component of the internal electrode, was passed. The non-oxidizing atmosphere gas is nitrogen gas at 100 liter / min and hydrogen gas at 1
4 with a mixed gas of liter / min at a speed of 50 ° C./h
The temperature was raised to 00 ° C and maintained for 2 hours. An attempt was made to degrease the ceramic molded body 21 in this gas. Therefore, the flow rate of the non-oxidizing atmosphere gas A supplied in Experimental Example 1 can be calculated to be about 1.7 times the total space volume of the support container 11 per second. [Comparative Example 1] [Comparative Example 2] For comparison with Experimental Example 1 described above, FIG. 10 shows a configuration of an internal circulation type degreasing apparatus often used in a conventional degreasing method.

In this internal circulation type degreasing device, the atmospheric gas A is supplied from the supply port D and discharged from the discharge port E. The atmosphere gas A is circulated by the motor fan 41 inside the degreasing device. The atmospheric gas A being circulated is heated to a predetermined temperature by the heater 42 installed inside the degreasing device.

Using an internal circulation type degreasing device having substantially the same size as in Experimental Example 1, 1/5 the number of samples in Experimental Example 1,
That is, degreasing was attempted for 27 support containers 11 each having 100 g of the above-mentioned Ni laminated chips loaded therein.

In Comparative Example 1, atmospheric air was supplied as the atmosphere gas A at 101 liter / min, and Comparative Example 2
In the above, 100 liter / min of nitrogen gas and 1 liter / min of hydrogen gas were flown. And Comparative Example 1
In Comparative Example 2 and Comparative Example 2, the atmospheric gas was 50 ° C. /
The temperature was raised to 400 ° C. at a rate of h, and this state was maintained for 2 hours to attempt degreasing.

The Ni laminated chips degreased by the three degreasing methods of Comparative Example 1, Comparative Example 2 and Experimental Example 1 were then ^{subjected to an} atmosphere of 1300 ° C. and an oxygen partial pressure of 1 × 10 ⁻¹⁰ atm for 2 hours. Was fired at. When the occurrence rate of defects is compared, the results are shown in Table 1 below.

[0036]

[Table 1]

As is clear from the results in Table 1, defects were generated in all the samples in Comparative Example 1 and about 1/5 of the samples in Comparative Example 2, whereas the degreasing method and degreasing apparatus according to the present invention produced defects. In Experimental Example 1, no defects were generated even though the processing amount was 5 times. Therefore, the degreasing method and the degreasing apparatus according to the present invention have the effect of suppressing heat generation due to the oxidative decomposition of the organic binder, the effect of eliminating the oxidative expansion of the metal powder, and the degreasing exhaust gas from the ceramic molded body to form ceramic It had the effect of reducing the probability of redeposition on the body surface. As a result, it is understood that the degreasing method and the degreasing apparatus of the present invention can reduce the occurrence of defects and significantly improve the productivity.

In the present experimental example, a mass flow meter was specifically used as the gas flow rate controller 14, but other devices such as a rotor meter may be used as long as the purpose of adjusting the gas flow rate can be achieved. I do not care.

In this experimental example, a mixed gas of nitrogen gas and hydrogen gas was used as the non-oxidizing atmosphere gas.
As long as the metal powder in the ceramic molded body to be degreased has a gas with an oxygen partial pressure that does not oxidize, a single gas of nitrogen gas, carbon dioxide gas, hydrogen gas, or a mixed gas of two or more thereof is used. It goes without saying that it may be used.

Further, in this embodiment, the metal powder in the ceramic molded body to be degreased is Ni, but if the condition that it is not oxidized by the atmospheric gas supplied is satisfied, the metal powder in the ceramic molded body is Is an alloy containing Ni as a main component, Pd, an alloy containing Pd as a main component, and C
It goes without saying that other metals such as alloys containing u and Cu as the main components may be used.

[Experimental Example 2] Next, an experimental example will be described in which the converted flow rate of the supplied non-oxidizing atmosphere gas per minute at 0 ° C. and 1 atm is more than the total space volume of the supporting container.

Degreasing apparatus main body B, internal structure of the degreasing apparatus, support container 11 and ceramic molded body 21 of this experimental example
Was exactly the same as that of Experimental Example 1 in shape and amount. That is, width 10 cm x length 15 cm x height 3 cm
100 g of Ni laminated chips are loaded on each of the alumina support containers 11 of FIG.
As shown in (c), 9 steps in the height direction, 5 steps in the length direction, and 3 steps in the width direction, a total of 135 pieces, were arranged in the degreasing apparatus main body B without gaps to obtain samples. Therefore, as in Experimental Example 1, the total space volume of the entire supporting container is 60750c.
m ³ (= 10 cm × 15 cm × 3 cm × 135 pieces = 6
0.75 liter).

Five sets of this sample were prepared, and nitrogen gas containing 1% hydrogen gas was flowed at five different flow rates (0 ° C., 1 atmospheric pressure equivalent flow rate) shown in Table 2 below to attempt degreasing. .

[0044]

[Table 2]

The Ni laminated chips degreased by the five degreasing methods were then fired for 2 hours in an atmosphere of 1300 ° C. and an oxygen partial pressure of 1 × 10 ⁻¹⁰ atm. It became like Table 3.

[0046]

[Table 3]

As is apparent from Table 3, Condition 1 and Condition 2 in which the non-oxidizing atmosphere gas was flowed at a flow rate of 0 ° C. and 1 atmospheric pressure at a flow rate of not more than the total space volume of the supporting container 11 per minute. When degreasing was carried out in step 1, defects were found in a large proportion in the ceramic molded body 21. On the other hand, the condition 3 in which the non-oxidizing atmosphere gas was flowed at a flow rate of 0 ° C. and a converted flow rate of 1 atm per minute at a flow rate of not less than the total space volume of the support container 11,
When degreasing was performed under the conditions 4 and 5, no defects were generated in the ceramic molded body 21.

From the above, the use of the degreasing method and the degreasing apparatus according to the present invention has the effect of suppressing the heat generation due to the oxidative decomposition of the organic binder and the effect of eliminating the oxidative expansion of the metal powder. Furthermore, non-oxidizing atmosphere gas at 0 ° C, 1
By making the converted flow rate of atmospheric pressure equal to or more than the total space volume of the support container per minute, it is possible to efficiently discharge the degreased exhaust gas from the ceramic molded body, and as a result, the degreased exhaust gas is discharged to the surface of the ceramic molded body. It had the effect of lowering the probability of redeposition. With these effects,
It has been found that the occurrence of defects in the ceramic compact 21 can be reduced.

In this embodiment, a mixed gas of nitrogen gas and hydrogen gas was used as the non-oxidizing atmosphere gas.
If the metal powder in the ceramic compact to be degreased has a gas oxygen partial pressure that does not oxidize, use nitrogen gas, carbon dioxide gas, hydrogen gas alone, or a mixed gas of two or more thereof. It goes without saying that it is okay.

Further, in this embodiment, the metal powder in the ceramic molded body to be degreased is Ni, but if the condition that it is not oxidized by the atmosphere gas supplied is satisfied, the metal powder in the ceramic molded body is Is an alloy containing Ni as a main component, Pd, an alloy containing Pd as a main component, and C
It goes without saying that another metal such as an alloy containing u or Cu as a main component may be used. [Experimental Example 3] Next, the dew point of the non-oxidizing atmosphere gas was 40 ° C.
Experimental examples limited to the above will be described. In Experimental Example 3, the degreasing device (FIG. 3) of the second embodiment shown in FIG. 3 was used. This degreasing device is obtained by adding a humidifier 31 to the degreasing device (FIG. 1A) of the first embodiment.

In Experimental Example 1 described above, 100 g of Ni laminated chips as the ceramic molded body 21 was loaded and degreased in one support container 11, but in Experimental Example 3, 1
Ni as the ceramic molded body 21 in one support container 11
200 g of laminated chips were loaded. As shown in FIG. 1C, this support container 11 has 9 steps in the height direction and 5 steps in the length direction.
A total of 135 steps, and three steps in the width direction, were stacked on the degreasing apparatus main body B shown in FIG. The non-oxidizing atmosphere gas is nitrogen gas at 99 liters / min.
And hydrogen gas is a mixed gas of 2 l / min in total of 101 l / min. Using a humidifier 31 shown in FIG. 3, this gas was humidified to have a dew point of 40 ° C. or higher, heated to 400 ° C. at a rate of 50 ° C./h, and maintained for 2 hours for degreasing. The other conditions were the same as in Experimental Example 1.

For comparison with Experimental Example 3, the following experiment was conducted as Comparative Example 3. That is, using the same internal circulation type degreasing device as in Comparative Example 2 above, 27 support containers 11 each having 200 g of Ni laminated chips loaded thereon were arranged and nitrogen gas of 99 was added.
A mixed gas of liter / min and hydrogen gas of 2 liter / min was caused to flow, the temperature was raised to 400 ° C. at a rate of 50 ° C./h, and the mixture was maintained for 2 hours for degreasing.

The Ni laminated chips degreased by the two degreasing methods were then fired for 2 hours in an atmosphere of 1300 ° C. and an oxygen partial pressure of 1 × 10 ⁻¹⁰ atm to compare the occurrence rate of defects. It looks like Table 4 below.

[0054]

[Table 4]

As is clear from the results shown in Table 4, in the comparative example 2 described above, the defect occurrence rate is 21%, whereas in the comparative example 3 in which the throughput is doubled as compared with the comparative example 2, The defect occurrence rate is 34%, which makes degreasing difficult. On the other hand, in Experimental Example 3 using the degreasing method and the degreasing apparatus according to the present invention, no defects occurred even though the treatment amount was further increased by 5 times as compared with Comparative Example 3.

From these facts, the degreasing method and the degreasing apparatus according to the present invention had the effect of suppressing the heat generation due to the oxidative decomposition of the organic binder and the effect of eliminating the oxidative expansion of the metal powder. In addition, it is possible to efficiently discharge the degreased exhaust gas from the ceramic molded body, and as a result, there is an effect that the probability that the degreased exhaust gas reattaches to the surface of the ceramic molded body is reduced. By such an effect, it is possible to reduce the occurrence of defects in the ceramic molded body,
It has also been found that it is possible to significantly improve productivity.

In this experimental example, as a non-oxidizing atmosphere gas,
Although a mixed gas of nitrogen gas and hydrogen gas was used, the present invention is not limited to this mixed gas. That is, if the metal powder in the ceramic molded body to be degreased is a gas having an oxygen partial pressure that does not oxidize and the dew point is 40 ° C. or higher,
It goes without saying that a single substance of nitrogen gas, carbon dioxide gas, hydrogen gas or a mixed gas of two or more thereof may be used.

Further, in this embodiment, the metal powder in the ceramic compact subjected to the degreasing treatment is Ni, but if the condition that it is not oxidized by the atmospheric gas supplied is satisfied, the metal powder in the ceramic compact is satisfied. Is an alloy containing Ni as a main component, Pd, an alloy containing Pd as a main component, and C
It goes without saying that other metals such as alloys containing u and Cu as the main components may be used.

[Experimental Example 4] The internal structure of the degreasing device, the ceramic molded body supporting container and the ceramic molded body used in Experimental Example 4 are exactly the same as those in Experimental Example 3 in shape and quantity.

That is, 200 g of the above Ni laminated chip was loaded as the ceramic molded body 21 in one support container 11 made of alumina having a width of 10 cm, a length of 15 cm and a height of 3 cm. As shown in FIG. 1 (c), this support container 11 has 9 steps in the height direction, 5 steps in the length direction, and 3 steps in the width direction.
A total of 135 stages were placed in the degreasing apparatus main body B without gaps to obtain samples.

Therefore, as in Experimental Example 1, the total space volume of the ceramic molded body supporting container was 60750 cm.
³ (= 10 cm × 15 cm × 3 cm × 135 pieces = 60.
75 liters).

Five sets of these samples were prepared, and each sample was moistened with nitrogen gas containing 2% hydrogen gas to a dew point of 40 ° C. or higher, and five flow rates (0 ° C., 1 atm) shown in Table 5 below. Degreasing was attempted at the converted flow rate).

[0063]

[Table 5]

The Ni laminated chips degreased by the five degreasing methods are then fired for 2 hours in an atmosphere of 1300 ° C. and an oxygen partial pressure of 1 × 10 ⁻¹⁰ atmosphere to compare the occurrence rate of defects. And it became like Table 6 below.

[0065]

[Table 6]

As is clear from the results of Table 6, Ni
The laminated chip is often degreased under conditions 1 and 2 in which a non-oxidizing atmosphere gas is circulated at a flow rate of 0 ° C. and 1 atmospheric pressure at a flow rate of not more than the total space volume of the support container 11 per minute. Occurrence of defects was recognized at a rate of. On the other hand, Ni
The laminated chip was degreased under conditions 3, 4, and 5 in which a non-oxidizing atmosphere gas was flowed at a flow rate of 0 ° C. and a pressure of 1 atm per minute at a flow rate of not less than the total space volume of the support container 11. In that case, no defects occurred.

From these facts, the degreasing method and the degreasing apparatus according to the present invention had the effect of suppressing the heat generation due to the oxidative decomposition of the organic binder and the effect of eliminating the oxidative expansion of the metal powder. Moreover, by setting the converted flow rate of the non-oxidizing atmosphere gas at 0 ° C. and 1 atm to be not less than the total space volume of the supporting container per minute, it is possible to efficiently discharge the degreased exhaust gas from the ceramic molded body. As a result, there is also an effect of reducing the probability that the degreased exhaust gas reattaches to the surface of the ceramic molded body. It has been found that such effects can reduce the occurrence of defects in the ceramic molded body.

In this experimental example, as a non-oxidizing atmosphere gas,
Although a mixed gas of nitrogen gas and hydrogen gas was used, the present invention is not limited to this mixed gas. That is, if the metal powder in the ceramic molded body to be degreased is a gas having an oxygen partial pressure that does not oxidize and the dew point is 40 ° C. or higher,
It goes without saying that a single substance of nitrogen gas, carbon dioxide gas, hydrogen gas or a mixed gas of two or more thereof may be used.

Further, in this experimental example, the metal powder in the ceramic molded body to be degreased is Ni, but if the condition that it is not oxidized by the atmospheric gas supplied is satisfied, the metal powder in the ceramic molded body is Is an alloy containing Ni as a main component, Pd, an alloy containing Pd as a main component, and C
It goes without saying that other metals such as alloys containing u and Cu as the main components may be used.

[Experimental Example 5] The internal structure of the degreasing device, the ceramic molded body supporting container and the ceramic molded body used in Experimental Example 5 are exactly the same as those in Experimental Example 3 in shape and amount.

That is, 200 g of the above-mentioned Ni laminated chip was loaded as a ceramic molded body 21 in one support container 11 made of alumina having a width of 10 cm, a length of 15 cm and a height of 3 cm. As shown in FIG. 1 (c), this support container 11 has 9 steps in the height direction, 5 steps in the length direction, and 3 steps in the width direction.
A total of 135 stages were placed in the degreasing device main body B without gaps to obtain samples.

Therefore, as in Experimental Example 1, the total space volume of the ceramic molded body supporting container was 60750 cm.
³ (= 10 cm × 15 cm × 3 cm × 135 pieces = 60.
75 liters).

Three sets of these samples were prepared, and each sample had a dew point adjusted to 5 ° C., 40 ° C. and 50 ° C.
Nitrogen gas containing 2% hydrogen gas at liter / min (0
Degreasing was attempted by applying a flow rate (° C, converted to 1 atm).

The Ni laminated chips degreased under the three humidifying conditions were then fired for 2 hours in an atmosphere of 1300 ° C. and an oxygen partial pressure of 1 × 10 ⁻¹⁰ atm, and the occurrence rate of defects was compared. It looks like Table 7 below.

[0075]

[Table 7]

As is clear from the results shown in Table 7, Ni
In the laminated chip, when the dew point of the non-oxidizing atmosphere gas was 5 ° C., defects were found in a large proportion. As a result of detailed examination of the sample in which these defects occurred, a large amount of organic components remained in the sample after degreasing due to insufficient degreasing. Then, the residual organic component is
It was revealed that gasification occurred and blistering occurred during the baking treatment at 0 ° C. for 2 hours. On the other hand, the dew point is 40 ° C and 5
At 0 ° C., no defects occurred.

From these facts, the degreasing method and the degreasing apparatus according to the present invention had the effect of suppressing the heat generation due to the oxidative decomposition of the organic binder and the effect of eliminating the oxidative expansion of the metal powder. Moreover, by setting the converted flow rate of the non-oxidizing atmosphere gas at 0 ° C. and 1 atm to be not less than the total space volume of the supporting container per minute, the degreased exhaust gas from the ceramic molded body can be efficiently discharged, As a result, there is an effect that the probability that the degreased exhaust gas reattaches to the surface of the ceramic molded body can be reduced. Further, in the degreasing treatment under a low oxygen partial pressure, the use of an atmosphere gas having a dew point of 40 ° C. or higher also had the effect of improving the degreasing efficiency. It has been found that these effects can reduce the occurrence of defects in the Ni laminated chip.

In this experimental example, as a non-oxidizing atmosphere gas,
Although a mixed gas of nitrogen gas and hydrogen gas was used, the present invention is not limited to this mixed gas. That is, if the metal powder in the ceramic molded body to be degreased is a gas having an oxygen partial pressure that does not oxidize and the dew point is 40 ° C. or higher,
It goes without saying that a single substance of nitrogen gas, carbon dioxide gas, hydrogen gas or a mixed gas of two or more thereof may be used.

Further, in this example, the metal powder in the ceramic molded body to be degreased is Ni, but if the condition that it is not oxidized by the atmospheric gas supplied is satisfied, the metal powder in the ceramic molded body is Is an alloy containing Ni as a main component, Pd, an alloy containing Pd as a main component, and C
It goes without saying that other metals such as alloys containing u and Cu as the main components may be used.

FIG. 4A is a sectional view showing the configuration of the third embodiment of the degreasing device according to the present invention, FIG. 4B is a sectional view taken along the line XY in FIG. 4A, and FIG. It is a perspective view of arrangement of a support container of a ceramics compact.

In this degreasing apparatus, the gas flow rate controller 14 for adjusting the flow rate of the gas flowing out from the nitrogen gas cylinder 15 and the hydrogen gas cylinder 16 and the gas preheating heater 12 for preheating the gas are the same as those in the degreasing apparatus shown in FIG. However, the degreasing device body B is different. As shown in FIG. 5, the degreasing device main body B is formed in a cylindrical shape, and inside thereof, a ceramic molded body support container 11 in which rising pieces are erected on both sides of a fan-shaped substrate is a donut shape. 8 pieces are combined into
It is stacked in a columnar shape. The pipe extending from the preheater is connected to the outer peripheral portion of the degreasing device body B.

In this degreasing apparatus, the non-oxidizing atmosphere gas A is blown from the outer peripheral portion of the cylindrical laminated body of the support container 11 toward the central portion, and is discharged from the central portion without being recirculated. This degreasing device has the effects that the quality of the product can be maintained, the space of the entire device can be saved, and the productivity is improved.

FIG. 6 (a) is a sectional view showing the configuration of the fourth embodiment of the degreasing device according to the present invention, and FIG. 6 (b) is a sectional view taken along the line XY in (a). The fourth embodiment is structurally almost the same as the third embodiment, but a pipe extending from the preheater is connected to the central portion of the degreasing device main body. Therefore, the non-oxidizing atmosphere gas A is used as the support container 11
The air is blown from the central part of the cylindrical laminated body toward the outer peripheral part, and is discharged without being recirculated. This degreasing device also has the effects that the quality of the product can be maintained, the space of the entire device can be saved, and the productivity is improved.

FIG. 8A is a sectional view showing the structure of the fifth embodiment of the degreasing device of the present invention, and FIG. 8B is a sectional view taken along line XY in FIG. 8A. FIG. 9A is a sectional view showing the configuration of the sixth embodiment of the degreasing device according to the present invention,
(B) is a XY line sectional view in (a).

The degreasing device of the fifth embodiment has a structure very similar to that of the third embodiment, but a humidifier 31 is provided between the preliminary heater 12 and the gas flow rate controller 14. Is different. The non-oxidizing atmosphere gas A of the fifth embodiment is blown from the outer peripheral portion of the degreasing apparatus main body B toward the central portion as in the third embodiment, and is not recirculated from the central portion. Is discharged.

The degreasing device of the sixth embodiment is the same as the fourth embodiment.
The configuration is very similar to that of the first embodiment, except that the humidifier 31 is provided as in the above. The non-oxidizing atmosphere gas A of the sixth example is blown from the central portion of the degreasing apparatus main body B toward the outer peripheral portion, as in the fourth embodiment.

Since the degreasing apparatus of the fifth and sixth embodiments has the humidifier 31, the space of the apparatus as a whole can be saved while maintaining the quality of the ceramic molded body, and the productivity can be improved. Is further improved.

[0088]

As described above, according to the method and structure of the present invention, a ceramic compact composed of ceramic powder, metal powder as an internal electrode, and an organic binder is heated, When removing the organic binder, a support container that supports the ceramic molded body is placed in the degreasing device without any gap to improve productivity,
As a result of realizing efficient forced convection and prompt discharge of degreased exhaust gas, defects in the ceramic compact can be significantly reduced.

[Brief description of the drawings]

1A is a cross-sectional view showing the configuration of a first embodiment of a degreasing device according to the present invention, and FIG. 1B is an X in FIG.
FIG. 3C is a cross-sectional view taken along the line Y, and FIG. 7C is a perspective view showing the arrangement of the support container of the present invention.

FIG. 2 is a perspective view of a support container that supports a ceramic molded body according to the present invention.

FIG. 3 is a sectional view showing a configuration of a second embodiment of a degreasing device according to the present invention.

FIG. 4A is a sectional view showing the configuration of a third embodiment of a degreasing device according to the present invention, and FIG.
FIG. 7C is a cross-sectional view taken along the line Y, and FIG. 7C is a perspective view of the arrangement of a support container that supports the ceramic molded body of the present invention.

FIG. 5 is a perspective view of a support container according to a third embodiment of the present invention.

FIG. 6A is a cross-sectional view showing the configuration of a third embodiment of the degreasing device according to the present invention, and FIG. 6B is an X in FIG.
FIG. 4 is a sectional view taken along line -Y.

FIG. 7 is a perspective view of a support container according to a fourth embodiment of the present invention.

FIG. 8A is a sectional view showing a configuration of a fifth embodiment of a degreasing device according to the present invention, and FIG.
FIG. 4 is a sectional view taken along line -Y.

9A is a cross-sectional view showing the configuration of a sixth embodiment of a degreasing device according to the present invention, and FIG. 9B is a sectional view taken along line X in FIG. 9A.
FIG. 4 is a sectional view taken along line -Y.

FIG. 10 is a sectional view of a conventional internal circulation type degreasing device.

[Explanation of symbols]

 11 Support Container 12 Preheat Heater 13 Preheat Heater 14 Gas Flow Controller 15 Nitrogen Gas Cylinder 16 Hydrogen Gas Cylinder 21 Ceramic Molded Body 31 Humidifier A Non-Oxidizing Atmosphere Gas B Degreaser Main Unit

Front page continued (72) Inventor Hidenori Kuramitsu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. A degreasing method for a ceramic molded body, comprising heating a ceramic molded body composed of ceramic powder, metal powder as an internal electrode, and an organic binder to remove the organic binder from the ceramic molded body. Oxidation-reduction equilibrium of the metal powder of the internal electrode in the formed body A non-oxidizing atmosphere gas having an oxygen partial pressure lower than the oxygen partial pressure is heated to a predetermined temperature, and this gas is used for a support container supporting the ceramic formed body. Ceramics in which air is blown from one direction and discharged without being recirculated, and the converted flow rate of the non-oxidizing atmosphere gas per minute at 0 ° C. and 1 atm is set to a flow rate not less than the total space volume of the supporting container. Degreasing method for molded products. 2. The degreasing method for a ceramic molded body according to claim 1, wherein the dew point of the non-oxidizing atmosphere gas is 40 ° C. or higher. 3. The degreasing method for a ceramic molded body according to claim 1 or 2, wherein the non-oxidizing atmosphere gas is nitrogen gas, carbon dioxide gas, hydrogen gas, or a mixed gas of two or more thereof. . 4. The internal electrode is any one of Pd or an alloy containing Pd as a main component, Ni or an alloy containing Ni as a main component, or Cu or an alloy containing Cu as a main component. Item 2. A method for degreasing a ceramic molded body according to item 2 or claim 3. 5. A degreasing device for use in heating a ceramic molded body composed of ceramic powder, metal powder as an internal electrode, and an organic binder to remove the organic binder from the ceramic molded body. A degreasing device main body in which a support container supporting the molded body is housed, and a total space volume of the supporting container supporting the ceramic molded body is equal to or higher than the degreasing device main body at a converted flow rate per minute of 0 ° C. and 1 atmosphere. Of the atmosphere gas, a mechanism for heating the atmosphere gas to a predetermined temperature in advance, and a mechanism for blowing the non-oxidizing atmosphere gas from one direction and discharging it without recirculation. Degreasing equipment. 6. The degreasing device according to claim 5, further comprising a mechanism for humidifying the non-oxidizing atmosphere gas. 7. The degreasing device main body is formed in a cylindrical shape, and a fan-shaped support container for supporting the ceramic molded body is laminated in a cylindrical shape inside the degreasing device main body. Item 7. A degreasing device according to item 6. 8. The non-oxidizing atmospheric gas is flowed from the outer peripheral portion of the cylindrical support containers to the central portion, and is discharged from the central portion without being recirculated. Degreasing equipment. 9. The non-oxidizing atmosphere gas is flowed from the central portion to the outer peripheral portion of the support containers laminated in a cylindrical shape, and is discharged from the outer peripheral portion without being recirculated. Degreasing equipment.